Alloys for tension bands

ABSTRACT

High quality factor, low torsion modulus alloys especially useful as tension bands for measuring instruments are composed essentially of platinum or palladium admixed with at least one element of Groups III, IV, V and VI of the Periodic Table excluding boron, carbon, nitrogen and oxygen.

United States Patent 1 Reiff 1 1 Sept. 23, 1975 [30] Foreign Application Priority Data Feb 11. 1972 Germany 2206397 [52] US. Cl. 75/172 R; 75/172 [51] Int. C1. C22C 5/04 [58] Field of Search 75/172 R. 172 G. 134 T.

[56] References Cited UNITEDSTATES PATENTS 2.222.544 11/1940 Spanner et a1 75/172 G X 2.946.679 7/1960 Darling 75/172 (1 X 3.245.781 4/1966 Durer et a1 75/172 R 3.374.123 3/1968 Masamoto et all 75/172 (1 X FOREIGN PATENTS OR APPLICATIONS 1.187.378 2/1965 Germany 75/172 (1 Primary E.\'aminerL. Dewayne Rutledge Assistant E.\'uminer-E. L. Weise Attorney. Agent. or FirmSpencer & Kaye [57] ABSTRACT High quality factor. low torsion modulus alloys especially useful as tension bands for measuring instruments are composed essentially of platinum or palladium admixed with at least one element ofGroups 111. IV. V and VI of the Periodic Table excluding boron. carbon. nitrogen and oxygen.

1 Claim, N0 Drawings ALLOYS FOR TENSION BANDS BACKGROUND OF THE INVENTION '1 I It is an object of the invention to provide new alloys consisting essentially-bf palladium or platinum and a "member ofGroupsIII, IV, Vand VI of thePeriodioTa- For measuring instruments having a rotatable mea--* tive laboratory instruments due to their high mechani cal sensitivity as regards shock and vibration and in view of their position dependency. With suitable structural measures for fastening the taut strips and for absorbing shocks and vibrations on the one hand and with improvements of the properties of the tape materials on "blegex-clu'ding. bororncarbon, nitrogen andoxygen.

It is a furtherobject of this invention to provide such alloys having a high quality. factor, low tension modulus the other hand, the mounting has now been perfected to such a degree that it can be used successfully today even in shockresistant switchboards. H

A taut strip or tension band must perform three functions: 4 i v 2. it providescurrent to "the measuring mechanism; and i i 3. it imparts the required resetting moment to the measuring mechanism. 1

1. it forms the bearing for the measuring mechanism; 1

The requirements placed on the taut strip due to the simultaneous performance of these three functions are I very high and often exclude one another due to their opposite nature. As a bearing, the strip must have the highest tensile strength without being brittle in order to be able to withstand shocks and vibrations. In the interest of high sensitivity, a small reset moment is required. This means that materials for taut strips must have as high as possible a breaking strength factor 0",; on the one hand and as low as possible a modulus of torsion G. The suitability of a material for tensioning belts is thus characterized by a parameter or quality factor 2 which is equal to the breaking strength divided by the square root of the modulus of torsion of the respective material.

In addition to the breaking strength and torsion modulus, the tension band material must be corrosion resistant, workable and easily solderable. For the production of high precision measuring instruments it is additionally important that the elastic after-effect and hysteresis be as low as possible. In certain cases in which low or normal demands are placed on the breaking strength of the taut strip suspension, it is desirable to reduce at least the torsion modulus as much as possible.

Heretofore, platinum/iridium alloys with an iridium content up to platinum/nickel alloys with a nickel content of 8 to 12.5% and gold/nickel alloys have been preferred for the taut strips. Alloys of the platinum metals (platinum, palladium, rhodium) with 5 to 40% iron, cobalt, nickel, tungsten, molybdenum, copper or silver and l to 30% iridium are suggested for fabrication of tension bands in German Pat. No. 1,152,826. Such alloys, according to this patent, exhibit torsion moduli in the order of 6300 with quality factors of about 2.50.

SUMMARY OF THE INVENTION The present invention relates to the use of an alloy consisting predominantly of palladium and/or platinum as the material for tensioning belts in measuring instruments having a rotatable measuring mechanism.

and good soldering properties and' thus especially suitable for use as tension bands for measuring instruments." l These and other objects will be apparent to those skilled in the art from the following description.

DETAILED DESCRIPTION The present invention is directed to the problem of providing alloys to be used as taut strip materials,

which exhibit a low torsion modulus and a'higher qua1-' ity factor than the alloys previously employed for this purpose.

This is accomplished in accordance with the present invention by certain new alloys predominantlyofpallai dium and/or'platinum, to which has beent added at least one element from Groups 111, IV, V and Vlof the Periodic Table, with the exception of boron. carbon, nitrogen and ox ygen, in such quantities that the corrosion resistance and workability of the primary component are preserved.

Alloys of palladium'with 3.5 to 4.5%

aluminum, pal.-

ladium withl0to 14% by weight antimony, palladium and preferably 5 to 25'wcight "/1 tellurim or of palladium andlpreferably 5 to 20% gallium. have been found to be'particularly advantageous. Particularly low torsion moduli and highest quality factors can be obtained with alloys which contain, in addition to at least one 01 ement of Groups 111, IV, V and VI of the Periodic Table, gold, silver and/or copper. Examples of such alloys are palladium with 2 to 6% by weight aluminum and l to 307: by weight copper and/or silver and palladium with 5 to 20% by weight gallium and 1 to 60% by weight copper.

Alloys having the composition of this invention have minimum torsion moduli in the order to 3000 and maximum quality factors of about 3.70 which are substantially more favorable than the values previously considered optimum.

Ten examples of alloys embodying this invention and the properties thereof are set forth in the following Table. The composition of the alloy according to components and weight percentages is given in the second column, the measured values for the torsion modulus (G) is shown in the middle column and the breaking tension or tensile strength (07,) is set forth in the fourth column. The quality factor (Z 'B/ VG.) appears in the fifth or last column.

Example Alloy G 0-,,

Composition (kp/mm) (kp/mm") 1 Pd/ln 88/12 4.090 145 2.27 2 Pd/Sn 90/10 4.100 138 2.16 3 Pd/Al 96/ 4 4.280 205 3.14 4 Pd/Sb 88/12 3.520 163 2.75

5 Pd/Te 90/10 2,940 154 2.84 6 Pd/Ga 90/10 3.740 171 2.80

7 92Pd/ 4 Al/ 4 Cu 4.960 216 3.06 8 92Pd/ 4 A1/4 Ag 3.140 181 3.23 9 76Pd/ 4 A1/20 Ag 3,880 216 3.47 10 8OPd/10 Gar/10 Cu 3.910 233 3.73

Examples 1 and 2 are alloys according to the present invention having a relatively low quality factor but the torsion moduli of these alloys lie substantially below the previously attainableflvalues which is to be desired. The other two-component alloys, Examples 34 have higher breaking strengths and higher quality factors than the alloys of Examples 1 and 2, with even lower values for torsion modulus for the alloys of Examples 4-6. In respect of the three-component alloys, Examples 7-l0, there is an even more significant improvement in the breaking tension and the quality factor, with the torsion modulus substantially lower than that of prior alloys for use in taut strips.

Although not shown in the Table, it is noteworthy that the alloys of Examples 3 and 7-10 have a good soldering property and a low elastic after-effect. Taking as the measure for soldering property the wetting angle between a strip of the alloy and a drop of solder, using rosin as the fluxing agent, that angle is 67 for palladium/aluminum 96/4 (Example 3), for 76% palladium/47: aluminum/% silver the angle is 15 and for 8071 palladium/10% gallium/10% copper the angle is l0. Under the same test conditions known alloys such as platinum/nickel 90/10 have a wetting angle of 23, gold/nickel 90/10 an angle of 23, gold/nickel 80/20 an angle of 14 and platinum/iridium 70/30 an angle of more than 90. Thus. the l0 wetting angle of'the 80% palladium/I07: gallium/lOf/r copper alloy is significantly below those of the taut strip alloys in use heretofore. Since a low wetting angle is a measure 'ofgo'od solderability. the solderability of the alloy palladium/l0% gallium/l0% copper is substantially better than that of the previously used taut strip alloys. The elastic after-effect for palladium/aluminum 96/4 is 0.02%, and for 80% palladium/10% gallium/l072 copper it is 0.05%. The after-effect behavior of the new alloys is thus at least as good as that of the previously used materials,

In addition to the additives used in the Table, one or more of the elements listed below can also be used, according to the present invention, as a component in these palladium and/or platinum alloys: germanium, silicon, bismuth, lead, tellurium, arsenic and selenium.

Other examples of alloys which possess a low tension modulus and other properties suitable for taut strips or tension bands are platinum with 2-3% tin, platinum with 1-3% aluminum or platinum with 525% cadmium.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

l. A low modulus of torsion, high quality factor taut strip for measuring instruments, sai-d taut strip being formed of an alloy which consists essentially of 80 percent by weight palladium, 10 percent by weight gallium, and I0 percent by weight copper, and the quality factor Z of the taut strip is 3.73. 

1. A LOW MODULUS OF TORSION, HIGH QUALITY FACTOR TUAT STRIP FOR MEASURING INSTRUMENTS, SAID TAUT STRIP BEING FORMED OF AN ALLOY WHICH CONSISTS ESSENTIALLY OF 80 PERCENT BY WEIGHT PALLADIUM, 10 PERCENT BY WEIGHT GALLIUM, AND 10 PERCENT BY WEIGHT COPPER, AND THE QUALITY FACTOR Z OF THE TAUT STRIP IS 3.73. 